diff --git a/.envrc b/.envrc
new file mode 100644
index 000000000..cffc922b0
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use flake . --impure
diff --git a/apps/cli/src/constants.ts b/apps/cli/src/constants.ts
index 95ba7a7d9..553e95dc6 100644
--- a/apps/cli/src/constants.ts
+++ b/apps/cli/src/constants.ts
@@ -195,5 +195,6 @@ export const ADDON_COMPATIBILITY = {
   fumadocs: [],
   opentui: [],
   wxt: [],
+  "nix-flake": [],
   none: [],
 } as const;
diff --git a/apps/cli/src/helpers/core/template-manager.ts b/apps/cli/src/helpers/core/template-manager.ts
index d6543b4d8..9c61994b7 100644
--- a/apps/cli/src/helpers/core/template-manager.ts
+++ b/apps/cli/src/helpers/core/template-manager.ts
@@ -36,6 +36,8 @@ export async function processAndCopyFiles(
       relativeDestPath = path.join(path.dirname(relativeDestPath), ".gitignore");
     } else if (basename === "_npmrc") {
       relativeDestPath = path.join(path.dirname(relativeDestPath), ".npmrc");
+    } else if (basename === "_envrc") {
+      relativeDestPath = path.join(path.dirname(relativeDestPath), ".envrc");
     }
 
     const destPath = path.join(destDir, relativeDestPath);
diff --git a/apps/cli/src/prompts/addons.ts b/apps/cli/src/prompts/addons.ts
index fb92e165c..ffa7304d4 100644
--- a/apps/cli/src/prompts/addons.ts
+++ b/apps/cli/src/prompts/addons.ts
@@ -63,6 +63,10 @@ function getAddonDisplay(addon: Addons): { label: string; hint: string } {
       label = "WXT";
       hint = "Build browser extensions";
       break;
+    case "nix-flake":
+      label = "Nix Flake";
+      hint = "Reproducible dev environment with Nix";
+      break;
     default:
       label = addon;
       hint = `Add ${addon}`;
@@ -74,7 +78,7 @@ function getAddonDisplay(addon: Addons): { label: string; hint: string } {
 const ADDON_GROUPS = {
   Documentation: ["starlight", "fumadocs"],
   Linting: ["biome", "oxlint", "ultracite"],
-  Other: ["ruler", "pwa", "tauri", "husky", "opentui", "wxt", "turborepo"],
+  Other: ["ruler", "pwa", "tauri", "husky", "opentui", "wxt", "turborepo", "nix-flake"],
 };
 
 export async function getAddonsChoice(addons?: Addons[], frontends?: Frontend[], auth?: Auth) {
diff --git a/apps/cli/templates/addons/nix-flake/_envrc.hbs b/apps/cli/templates/addons/nix-flake/_envrc.hbs
new file mode 100644
index 000000000..e3fecb324
--- /dev/null
+++ b/apps/cli/templates/addons/nix-flake/_envrc.hbs
@@ -0,0 +1,2 @@
+use flake
+
diff --git a/apps/cli/templates/addons/nix-flake/flake.nix.hbs b/apps/cli/templates/addons/nix-flake/flake.nix.hbs
new file mode 100644
index 000000000..43f639bb8
--- /dev/null
+++ b/apps/cli/templates/addons/nix-flake/flake.nix.hbs
@@ -0,0 +1,77 @@
+{
+  description = "{{projectName}} devshell";
+
+  inputs = {
+    nixpkgs = {
+      url = "github:NixOS/nixpkgs/nixos-unstable";
+    };
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      mkShellFor = system:
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+        in
+        pkgs.mkShell {
+          packages = [
+            # package manager
+{{#if (eq packageManager "bun")}}
+            pkgs.bun
+{{else}}
+            pkgs.nodejs_22
+{{/if}}
+{{#if (eq packageManager "pnpm")}}
+            pkgs.pnpm
+{{/if}}
+
+            # backend runtime (if different from package manager)
+{{#if (and (eq runtime "bun") (ne packageManager "bun"))}}
+            pkgs.bun
+{{/if}}
+{{#if (and (eq runtime "node") (eq packageManager "bun"))}}
+            pkgs.nodejs_22
+{{/if}}
+{{#if (eq runtime "workers")}}
+            pkgs.wrangler
+{{/if}}
+
+            # database tooling
+{{#if (eq dbSetup "docker")}}
+            pkgs.docker-compose
+{{/if}}
+{{#if (and (eq database "postgres") (eq dbSetup "docker"))}}
+            pkgs.postgresql
+{{/if}}
+{{#if (and (eq database "mysql") (eq dbSetup "docker"))}}
+            pkgs.mariadb
+{{/if}}
+{{#if (and (eq database "mongodb") (eq dbSetup "docker"))}}
+            pkgs.mongosh
+{{/if}}
+{{#if (eq dbSetup "turso")}}
+            pkgs.turso-cli
+{{/if}}
+{{#if (eq dbSetup "supabase")}}
+            pkgs.supabase-cli
+{{/if}}
+          ];
+
+          shellHook = ''
+            if [ -n "$PS1" ]; then
+{{#if (eq packageManager "bun")}}
+              echo "bun: $(bun --version)"
+{{else}}
+              echo "node: $(node --version)"
+{{/if}}
+            fi
+          '';
+        };
+    in
+    {
+      devShells.x86_64-linux.default = mkShellFor "x86_64-linux";
+      devShells.aarch64-linux.default = mkShellFor "aarch64-linux";
+      devShells.x86_64-darwin.default = mkShellFor "x86_64-darwin";
+      devShells.aarch64-darwin.default = mkShellFor "aarch64-darwin";
+    };
+}
diff --git a/apps/cli/test/addons.test.ts b/apps/cli/test/addons.test.ts
index 862763603..83a759e88 100644
--- a/apps/cli/test/addons.test.ts
+++ b/apps/cli/test/addons.test.ts
@@ -6,7 +6,7 @@ import { expectError, expectSuccess, runTRPCTest, type TestConfig } from "./test
 
 describe("Addon Configurations", () => {
   describe("Universal Addons (no frontend restrictions)", () => {
-    const universalAddons = ["biome", "husky", "turborepo", "oxlint"];
+    const universalAddons = ["biome", "husky", "turborepo", "oxlint", "nix-flake"];
 
     for (const addon of universalAddons) {
       it(`should work with ${addon} addon on any frontend`, async () => {
@@ -290,6 +290,7 @@ describe("Addon Configurations", () => {
       "husky",
       "turborepo",
       "oxlint",
+      "nix-flake",
       // Note: starlight, ultracite, ruler, fumadocs are prompt-controlled only
     ];
 
diff --git a/apps/web/content/docs/cli/options.mdx b/apps/web/content/docs/cli/options.mdx
index 824087d38..a8037896f 100644
--- a/apps/web/content/docs/cli/options.mdx
+++ b/apps/web/content/docs/cli/options.mdx
@@ -296,6 +296,7 @@ Additional features to include:
 - `ultracite`: Ultracite configuration
 - `oxlint`: Oxlint + Oxfmt (linting & formatting)
 - `ruler`: Centralize your AI rules with Ruler
+- `nix-flake`: Reproducible dev environment with Nix
 - `opentui`: OpenTUI components
 - `wxt`: WXT browser extension framework
 
diff --git a/apps/web/content/docs/index.mdx b/apps/web/content/docs/index.mdx
index f6377d381..99e8b8e62 100644
--- a/apps/web/content/docs/index.mdx
+++ b/apps/web/content/docs/index.mdx
@@ -311,7 +311,7 @@ See the full list in the [CLI Reference](/docs/cli). Key flags:
 - `--api`: trpc, orpc, none
 - `--auth`: better-auth, clerk, none
 - `--payments`: polar, none
-- `--addons`: turborepo, pwa, tauri, biome, husky, starlight, fumadocs, ultracite, oxlint, ruler, opentui, wxt, none
+- `--addons`: turborepo, pwa, tauri, biome, husky, starlight, fumadocs, ultracite, oxlint, ruler, opentui, wxt, nix-flake, none
 - `--examples`: todo, ai, none
 
 ## Next Steps
diff --git a/apps/web/src/lib/constant.ts b/apps/web/src/lib/constant.ts
index 776c7ac2e..0c7f1980a 100644
--- a/apps/web/src/lib/constant.ts
+++ b/apps/web/src/lib/constant.ts
@@ -557,6 +557,14 @@ export const TECH_OPTIONS: Record<
       color: "from-emerald-500 to-emerald-700",
       default: false,
     },
+    {
+      id: "nix-flake",
+      name: "Nix Flake",
+      description: "Reproducible dev environment with Nix",
+      icon: "",
+      color: "from-sky-500 to-sky-700",
+      default: false,
+    },
     {
       id: "turborepo",
       name: "Turborepo",
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 000000000..8e486ee8c
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1766201043,
+        "narHash": "sha256-eplAP+rorKKd0gNjV3rA6+0WMzb1X1i16F5m5pASnjA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "b3aad468604d3e488d627c0b43984eb60e75e782",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 000000000..6f6db71bd
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,37 @@
+{
+  description = "create-t-stack devshell flake";
+
+  inputs = {
+    nixpkgs = {
+      url = "github:NixOS/nixpkgs/nixos-25.11";
+    };
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      mkShellFor = system:
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+        in
+        pkgs.mkShell {
+          packages = [
+            pkgs.bun
+            pkgs.nodejs_22
+          ];
+
+          shellHook = ''
+            if [ -n "$PS1" ]; then
+              echo "bun: $(bun --version)"
+            fi
+          '';
+        };
+    in
+    {
+      # explicit nested outputs per system
+      devShells.x86_64-linux.default = mkShellFor "x86_64-linux";
+      devShells.aarch64-linux.default = mkShellFor "aarch64-linux";
+      devShells.x86_64-darwin.default = mkShellFor "x86_64-darwin";
+      devShells.aarch64-darwin.default = mkShellFor "aarch64-darwin";
+    };
+}
+
diff --git a/packages/types/src/schemas.ts b/packages/types/src/schemas.ts
index c6462ec48..f707e1cc6 100644
--- a/packages/types/src/schemas.ts
+++ b/packages/types/src/schemas.ts
@@ -44,6 +44,7 @@ export const AddonsSchema = z
     "oxlint",
     "opentui",
     "wxt",
+    "nix-flake",
     "none",
   ])
   .describe("Additional addons");